Radio warning system



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RADIO WARNING SYSTEM Filed Aug. 16, 1962 3O CPS P. C. GOLDMARK ETAL 4 0(JP-S \20 ATT. PROGRAM /4 INPUT/6 [5 BATTERY CHARGE 26 ATT.

June 21, 1966 AC. SOURCE TO SWITCHES 53,84 ,4 INVENTORS.

PETER C. GOLDMARK, ABRAHAM A. GOLDBERG a BY BENJAMIN B. BAUER 4 44M 77 24, M

their A7'7URNEYS United States Patent 3,257,617 RADIO WARNING SYSTEMPeter C. Goldmark, Abraham A. Goldberg, and Benjamin B. Bauer, Stamford,Conn., assignors to Columhia Broadcasting System, Inc, New York, N.Y., acorporation of New York Filed Aug. 16, 1962, Ser. No. 217,347 5 Claims.(Cl. 325-364) This invention relates to alarm systems, and moreparticularly to a warning system utilizing radio broadcast transmissionand reception facilities for advising'the public of emergencyconditions.

Radio broadcasting facilities enable information to be rapdilycommunicated to large segments of the population at a moments notice. Intimes of emergency, radio broadcasts have proved to be invaluable aidsin minimizing the loss of life and property. Civilian defenseauthorities, charged with the protection of the public in the event ofattack from without, have recognized this ability and have set asidespecific broadcast channels, known as the Conelrad frequencies, fordissemination of information and instructions in time of emergency.These frequencies are within the normal reception band of home radioreceivers and the listener is required to tune his receiver to th properfrequency to receive the broadcasts. Moreover, he must depend upon otherwarning devices, such as sirens, etc. to apprise him of the existence ofan emergency and the need to tune his receiver to the emergencyfrequency.

Stand-by receiver arrangements have been proposed in the past to enableradio warnings to be received auto- 'matically, without requiring theuser to tune in to a specified frequency. Most of these, however, takethe form of completely separate receiver units intended only for thereception of warning information. The user is thus required to purchasewhat amounts to a complete radio receiver that has no utility except intime of emergency. Furthermore, known stand-by receivers often requirelarge amounts of power to maintain them in the standby condition andalso, often require aconscious act of the user to place it in standbyoperaiton. All of these factors contribute towards making these devicesexpensive in both initial cost and maintenance, and of lessereffectiveness as warning devices.

Accordingly, it is the primary object of the present invention toprovide an improved radio warning system which avoids the foregoingdisadvantages of the prior art system.

A further object of the present invention is to provide a radio warningsystem including a radio receiver which may also be used for standardbroadcast reception and which, when not receiving standard broadcasts,is automatically placed in the standby condition.

Still another object of the present invention is to provide a radiowarning system utilizing low frequency tones for controlling theoperation of the stand-by receiver.

An additional object of the present invention is to provide a radiowarning system htaving a receiver which a special frequency assignedonly for emergency purposes.

The receiver of the system is a standard superheterodyne receiver,transistorized for low power drain, and modified to be receptive toemergency signals when not receiving normal broadcasts. The lattermodification is effected by providing an auxiliary tuning control, avolume control bypass, and a muting and unmuting circuit for the outputaudio amplifier, all actuated simultaneously upon operation of thenormal ON-OFF switch of the receiver .to its OFF position. Thus, withthe control switch in what corresponds to the ON position, the receivermay be tuned to any desired broadcast frequency and normal radio signalsare received and reproduced at the loudspeaker. It is assumed, that intimes of emergency, information -will be broadcast on all broadcastfrequencies, as well as any special emergency frequencies, and thelistener will thus be kept informed during normal listening.

When the listener no longer cares to hear the normal broadcast, he turnsthe switch to what corresponds to the OFF position, in the usual manner.However, instead of turning off the power supply to th receiver, thethrowing of the switch (1) tunes the receiver to a predeterminedfrequency, (2) bypasses the volume control associated with the detectorin the receiver, and (3) disconnects the bias circuit of the outputaudio amplifier from the normal bias to the output of a special toneresponsive network coupled to the output of the receiver detector. Thelatter mutes the output amplifier except when the low frequency tone isreceived.

In the absence of an emergency broadcast and with the receiver in thestand-by condition as described above, no sound at all is detectable atthe loud-speaker, although all circuits are ready to receive signals atthe predetermined frequency. Preferably, the receiver circuits aretransistorized, in well known fashion, to minimize the power drained inthis condition. Upon transmission of an emergency message, along withwhich is sent the loW frequency tone, a selective amplifier and detectorseparates the low frequency tone and derives a voltage therefrom whichis applied to the output amplifier to render it operative. The emergencyinformation signals may now be amplified and rendered audible. As longas the tone is transmitted along with the information, an audible outputwill be available from the loud-speaker. As soon as the emergencybroadcast ceases, the tone is removed and the circuit automaticallyreturns to its stand-by condition without any additional manualoperation. When it is desired to again listen to a standard broadcast,the control switch is simply tuned to what corresponds to theconventional ON position.

According to the invention, two different types of emergency informationsignals may be transmitted: one in which only emergency warnings aresent and another in which both warning and more general information suchas news releases etc. are transmitted. To accommodate both selectivelyat the receiver, each type of broadcast is accompanied by its individuallow frequency tones. The receiver is provided with a separate switchwhich renders the tone detecting circuitry responsive to just the onetone corresponding to the emergency warning information, or either ofthe tones which will enable the receiver to reproduce whatever type ofemergency information is being broadcast.

The foregoing and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription thereof when taken in conjunction with the accompanyingdrawings, in which:

FIGURE 1 is a block diagram of the transmitter usable with the presentinvention;

FIGURE 2 is a block diagram of the receiver of the present invention;

tive, may be special equipment operative only in emergency situations.In either case, the carrier wave transmitted will be of a predeterminedfrequency assigned in accordance with governmental regulations.

Program input signals, which in the case of a commercial broadcastingstation may consist of music, drama, public events, etc., are applied tothe input terminal 14 and through the contacts 16 of a double poleswitch to modulate the carrier wave in known manner for broadcastingpurposes. Under normal broadcasting conditions, the programmaterial willproduce 100% modulation of the carrier wave, in accordance withconventional operation.

When it is desired to broadcast signals warning of an emergencycondition, the contacts 16 of the double pole switch are thrown to theirupper position in contact with the terminals 20. Between the terminals20 are connected an attenuator 22 and a source of low frequency tone,for example, a frequency of 40 cycles per second. The attenuator 22 andthe tone source 24 are so regulated that the program input signal willprovide 80% modulation of the transmitted carrier and the tone signal20%. The transmitted signal will thus consist of a carrier modulatedboth by the low frequency tone and emergency information.

An alternate tone source 30, of a frequency different than that ofsource 24, e.g., cycles per second, may be connected in series with anattenuator 28 between a third set of terminals 26. With the contacts 16on the terminals 26, an alternate type of emergency program informationmay be applied to the transmitter. As in the previous case, the programinformation may supply 80% modulation with the remaining 20% beingprovided by the 30 cycle source.

Assuming that the broadcast station is transmitting its usual program,and an emergency situation arises warranting the transmission of warningsignals, the operator merely moves the contacts 16 to the desired pairsof terminals 20 or 26 and applies the emergency announcements to theprogram input. For example, with the switch arms on the terminals 20,the program input may consist of emergency warnings of extreme urgency,while with the arms on the terminals 26, the information may be oflesser urgency, with news briefs etc. interspersed therein to provideinformation relative to an expected or possible danger.

The receiving apparatus according to the invention is illustrated inFIGURE 2. A receiving antenna 40, which may be of the ferrite sticktype, couples the received carrier wave to the receiver input tunedcircuit including inductance 42 and capacitor 44. The. conventionallocal oscillator tuned circuit is shown as comprising a coil 52 andassociated capacitor 54. The capacitors 44 and 54 are gang tunable inthe usual manner to select the broadcast frequency to be received. Thereceived signal and the local oscillator frequency are supplied to theconverter 60 which in conventional fashion provides an intermediatefrequency signal. The latter is supplied through first and second I.F.amplifiers 62, 64, and thence to a detector 66. The latter derives theaudio frequency modulating signals from the intermediate frequencysignal and couples them through a conventional volume control 68 to afirst audio amplifier stage 70. The output of the latter is applied tothe audio power amplifier 72, which in the embodiment shown is of thepush-pull type, and thence to the loud-speaker 76. It will be realizedthat the apparatus thus far described is a conventional broadcastreceiver and each of the elements thereof may take any suitable formknown in the art.

The receiver and local oscillator tuned circuits are provided withadditional capacitors 46 and 56, respectively. A switch S1 selectivelyconnects capacitor 44 or 46 in parallel with the coil 42, while asimilar switch S2 in the oscillator tuned circuit likewise connectseither the capacitor 54 or 56in parallel with the coil 52. As will beexplained more fully hereinafter, with the switches S1 and S2 in the Nor normal position shown, the receiver may be tuned to any existingbroadcast frequency in the manner of the conventional radio receiver.With the switches in the A or alarm position, connected to capacitors 46and 56 respectively, the receiver is tuned to the predeterminedfrequency on which emergency signals are broadcast. The capacitors 46and 56 are shown as being gang tunable whereby they may be adjusted toset their respective tuned circuits to the predetermined warningfrequency then in use.

A third switch member S3 is provided between the detector and the firstaudio amplifier 70. In the N position, the detector is connected to theamplifier 70 through the volume control 68, whereby the output volumemay be adjusted by control of the potentiometer in the usual manner.With the switch S3 in the A position, the volume control 63 iscompletely bypassed and rendered ineffective.

The output of the first audio amplifier 70 is also connected in parallelto the inputs of a pair of frequency selective amplifiers and 82. Theamplifier 80 is tuned to select only 40 c.p.s. signals while theamplifier 82 is responsive only to 30 cycle tones. A switch 84 connectsthe outputs of the amplifiers 80, 82 to the input of a detector 86. Asevident from the drawing, the switch 84 and the associated contacts atthe output of the amplifiers are so arranged that in one position, onlythe 40 cycle output is connected to the detector 86 while in the otherposition, either or both the 40 cycle and 30 cycle tones will besupplied to the detector. The detector 86 produces a unidirectionalvoltage of a given magnitude in response to the application thereto of atone signal from either of the amplifiers 80, 82.

An operating bias source for the power amplifier 72 is connected throughthe N contact of the switch $4, the A contact coupling the output of thedetector 86 to the amplifier bias control elements.

With the switches S1 through 54, which are ganged for simultaneousactuation, in the normal, or N positions as shown, the receiver ofFIGURE 2 operates as an ordinary broadcast receiver. The station may beselected by tuning of the capacitors 44, 54 in the usual manner and thevolume of the audio output may be controlled by means of the volumecontrol 68. When the switches S1 through S4 are thrown to the alarm, orA position, which will correspond to the OFF position of the usualON-OFF switch of the conventional radio receiver, operation of thecircuit is changed. The switches S1 through S4 may conveniently bestacked for operation by a single control shaft, in well known manner.

With the switches S1 through S4 in their alarm positions, the tunablecircuits of the receiver are tuned to the emergency frequency of thetransmitter 10 (FIGURE 1). At the same time, the output of the detector66 is connected directly to the input of the amplifier 70, bypassing thevolume control 68, and the output of detector 86 is applied to the biascontrol of the power amplifier 72, 74 in place of the normal biassupply. As will be explained in connection with FIGURE 3, changing ofthe switches from the normal to alarm positions does not disconnect thepower supply, and all of the circuits of the receiver remain in theiractive condition.

In the absence of a received signal from the transmitter 10 modulatedwith a suitable low frequency tone, no operating bias is applied to theamplifier 72 from the output of the detector 86 and the receiver is thusmuted. No audible output is provided by the speaker to disturb orinterfere with the activities of the user. When an alarm signal istransmitted with a low frequency tone modulated thereon, such as whenthe switch 16 of FIG- URE 1 is in contact with the terminals 20, thetone as well as the emergency information thereon is detected in thedetector 66 and applied to, the audio amplifier 70 and thence to thepower amplifiers. The tones are of sufliciently low frequency that theywill be inaudible on all but the very highest fidelity receivers, andwill not interfere with the intelligibility of the alarm broadcast.

The 40 cycle tone is also supplied to the amplifier 80, which rejectsother audio signals, and through switch 84 to the detector 86. The DC.voltage provided by the latter in response to the tone is applied asoperating bias to the power amplifier 72 through contact A of switch S4,rendering the amplifier operative and enabling the information contentof the emergency signal to be amplified and applied to the loud-speaker76. The user is thus warned of the alarm condition. Since the volumecontrol 68 has been bypassed by switch S3, the warning will be atsuflicient volume to awaken the user if asleep or to attract hisattention if he happens to be at some distance from the receiver.

As discussed briefly hereinabove, if the switch 16 is in contact withthe terminals 26, a 30 cycle tone Will be transmitted along with adifferent form of emergency information. The user can select, by meansof switch 84, whether he wishes to be advised of the more generalemergency information that is accompanied by the 30 cycle tone, or onlyof the urgent alarm signals accompanied by the 40 cycle tone. In theupper position shown in the drawings, only the 40 cycle tone will bereceived. In the lower position, both types of emergency informationwill be made available to the user.

It will be appreciated from the foregoing, that with the gang-controlledswitches SI through S4 replacing the normal ON-OFF switch of aconventional radio receiver, the user cannot, through any lapse ofmemory, forget to put the receiver in the stand-by condition. The almostreflex action of turning the receiver switch to the conventional OFFposition when it is no longer desired to listen to normal broadcastprograms, effects the conversion. While in the latter condition, thereceiver will be muted except during those periods in which emergencyinformation is actually being transmitted. v The muting and unmuting ofthe receiver amplifier is performed completely automatically andrequires no user attention. When the user desires to hear a standardbroadcast program again, he merely switches the knob to the normal ONposition and tunes the receiver in the normal manner.

Although the circuitry illustrated in FIGURE 2 is entirely feasible foruse with vacuum tubes, the use of transistors as the active componentsis more desirable in view of their low power consumption. This is ofspecial importance under emergency conditions in which the commercialpower sources may be no longer available.

A suitable power supply for the receiver of FIGURE 2 is shown in FIGURE3. Where normal 117 volt 60 cycle AC. power is available, the plug 90may connect such source to a battery charger 92 which, in known manner,supplies a DC. charging current to the storage battery 94. The'chargermay conveniently consist of a transformer having its secondary supplyingalternating current at suitable voltage to a simple rectifying devicefor conversion to direct current. The battery 94, which may be anickel-cadmium cell, is shown with its positive terminal grounded andits negative terminal connected to the receiver circuits. It will berealized, of course, that suitable voltage divider arrangements will beprovided to distribute the voltages at the proper. amplitudes to thevarious circuit elements in the receiver.

The battery charger 92 may also be provided with a low voltage outputwinding coupling alternating current over conductor 96 and through theswitch S5 to a flashlight or similar light source 98. The switch S5, inthe Off position, will be connected to the low voltage winding on thebattery charger 92. This voltage is suflicient only to produce a feebleglow of the light 98, to indicate that the battery charger is receivingpower from the AC. source and also that the battery 94 is being chargedby the charger 92. It thus serves as an indication that the circuit isfunctioning.

With the switch S5 in the On position, the light cell 98 is connecteddirectly across the battery 94 causing it to glow brightly, therebyproviding an auxiliary light source. Under emergency conditions, when itmay be impossible or dangerous tomaintain existing light sources, theauxiliary light source 98 may provide valuable assistance.

The power supply shown in FIGURE 3 enables the receiver to be operatedwith a connection to the AC. supply mains where power is available, oras a portable, functioning on the battery 94 only. Since the battery 94is of the rechargeable type, it can be replenished when A.C. power isrestored or made available again. Therefore, the user may carry thereceiver with him at all times in whatever environment he happens to be.As an additional safeguard, the battery holding structure for the cell94 may be made of a suitatble size to accept standard flashlight cells,should they become necessary.

A modification of the control switch arrangement of the circuit ofFIGURE 2 is illustrated in FIGURE 4, wherein like reference numeralshave been used to indicate elements corresponding to those of FIGURE 2.In FIGURE 4, the receiver and oscillator tuned circuits are eachprovided with only a single tunable capacitor 102 and 104 respectively.A push button control 108 is provided in the receiver housing to switchthe receiver between the alarm and normal positions.

In accordance with a conventional construction, the push button isprovided with an arm 110 having a detent portion 112 along the loweredge thereof. The latter is formed with a sloping forward edge and avertical trailing edge for engaging a resiliently mounted locking member114. In conventional push button tuning arrangements, a plurality ofsuch buttons will be placed side by side cooperating with a singlemember 114. All of the push buttons will also be urged by spring means(not shown) to normally assume their outer or extended position. Thus,the pressing of any one button to its inward or depressed position, willinitially force the bar 114 downwardly, by virtue of the sloping forwardedge of the detent 112, and thus release the push button previouslyretained thereby in its forward position. The newly pressed button thenlocks in its forward position.

In the embodiment of FIGURE 4, the button 108 may be comparable to theOFF push button of conventional push button receivers. However, insteadof disconnecting the circuits from the power supply, pressing of thebutton simultaneously adjusts the capacitors 102, 104 in the receivertuned circuits to the predetermined frequency of the transmitter 10, andchanges the switches S3 and S4 from the normal to the alarm positions.The receiver circuit is now readied in stand-by condition to receiveemergency broadcasts. When the user desires to listen to standardbroadcasts again, he presses the push button corresponding to thedesired station, thereby releasing the push button 108 and tuning thereeiver to the desired program. At the same time the switches S3 and S4are returned to their normal position.

It will be seen from the foregoing, that the present invention providesa warning system adaptable to standard present day broadcast procedures,which enables wide spread dissemination of alarm information with aminimum of additional equipment at the transmitter and a simple,economically operated receiver for the individual listener. The latter,in addition to being able to receive alarm broadcasts, also function asa conventional broadcast receiver whenever desired. Moreover, transi-'tion between the normal broadcast and alarm broadcast conditions of thereceiver is effected in a manner which does not permit an act ofomission by the user from disabling the alarm circuit. While in thealarm condition, the audio portion of the receiver remains muted untilalarm signals are actually received. The receiver may be operated froman AC. source or from its self-contained battery and is completelyportable.

Although one type of conventional receiver circuit has been illustrated,it will be understood that the invention is applicable to a wide rangeof variations thereof, and it is intended that the scope of theinvention not be limited except as set forth in the appended claims.

We claim:

1. A radio receiver usable for both conventional broadcast reception andfor reception of warning signals comprising, circuit means tunable '-toboth broadcast and warning signals, detecting means for deriving audiofrequency signals from the received signals, a volume control coupled tosaid detecting means for controlling the amplitude of said audiosignals, amplifier means for said audio signals, means for controllingthe operability of said amplifier means, selective circuit means coupledto receive audio frequency signals derived by said detecting means andresponsive to signals of a predetermined frequency to develop an outputpotential, and two-position control switch means operable in oneposition to connect the receiver tunable circuit means for conventionalbroadcast reception, couple the detector output through said volumecontrol to said amplifier means, and render said amplifier meansoperative, and operable in the other position to tune said receiver forwarning signal reception, couple the detector output directly to saidamplifier means, and couple said selective circuit means to saidcontrolling means for said amplifier means to render the latter operablein response to said output potential, said control switch meanscorresponding to a conventional on-off, switch whereby switching of saidreceiver to discontinue conventional broadcast reception necessarilyconnects the receiver for warning signal reception.

2. Apparatus according to claim 1 wherein said tunable circuit meansinclude separate tuning elements for conventional broadcast and warningsignal reception, respectively, and wherein said control switch meanscomprises a plurality of simultaneously actuated switching elements, oneof which is movable between a first position in which said conventionalbroadcast tuning elements are selected and a second position in whichsaid warning signal tuning elements are selected, a second of which ismovable between a first position in which said volume control isoperably connected between said detector and said amplifier means and asecond position in which said detector is coupled directly to saidamplifier means bypassing said volume control, and a third of which ismovable between a first position in which said amplifier means isrendered continually operable and a second position in which saidselective circuit means is coupled to said controlling means to rendersaid amplifier means operable in response to said output potential.

3. In a radio receiver for use in a radio warning system having tunablecircuit means, detecting means for deriving audio frequency signals fromthe received signals, and amplifier means for said audio frequencysignals, the improvement comprising control switch means having only twopositions and operable between a first position in which said receiver,including said audio amplifier means, is connected and rendered operablefor reception of standard broadcast signals, and a second position inwhich said receiver is connected and tuned for reception of warningsignals on a predetermined frequency and said audio amplifier means isrendered operable only in re sponse to a given audio frequency componentderived by said detector, said control switch means corresponding to aconventional on-off switch whereby switching of said receiver todiscontinue standard broadcast reception necessarily connects and tunessaid receiver for warning signal reception.

4. A radio receiver for reception of both conventional program andwarning signals, the latter being modulated on a carrier frequencywithin the broadcast band, comprising input circuits continuouslytunable over the broadcast band, detecting means for deriving audiofrequency signals from the received signals, amplifier means for saidaudio frequency signals, manually operative pushbutton actuating meansin said receiver operable in one position to adjust said tunablecircuits to select a carrier frequency on which said warning signalswill be broadcast and to connect said amplifier means to be operableonly during the occurrence of warning signals, andv in another positionto render said amplifier means continuously operable and responsive toboth conventional program and warning signals.

5. In a radio receiver for use in a radio warning system having tunablecircuit means, detecting means for driving audio frequency signals fromthe received signals, volume control means, and amplifier means for saidaudio frequency signals, the improvement comprising twoposition controlswitch means operable between a first position in which said saidreceiver is connected and rendered operable for reception of standardbroadcast signals with said volume control means operatively coupledbetween said detecting means and said amplifier means, and a secondposition in which said receiver is connected and tuned for reception ofwarning signals on a predeterrnied frequency, said volume controlrendered inoperative whereby the output of said detector is coupleddirectly to said amplifier means, and said audio amplifier is renderedoperable only in response to a given audio frequency component derivedby said detector, said control switch means corresponding to aconventional on-otf switch whereby switching of said receiver todiscontinue standard broadcast reception necessarily connects and tunessaid receiver for warning signal reception.

References Cited by the Examiner UNITED STATES PATENTS 2,344,618 3/1944Koch 325466 X 2,368,778 2/1945 Purington 325-466 X 2,630,525 3/ 1953Tomberlin et a1. 325466 X 2,709,254 5/1955 Halstead 325466 X 2,958,77011/1960 Davidson et al. 343228 X 2,993,991 7/1961 Lundahl 325-4663,009,059 11/1961 Stratton et al. 325-364 ROBERT H. ROSE, PrimaryExaminer.

DAVID G. REDINBAUGH, Examiner.

r R. F. ROTELLA, R. LINN, Assistant Examiners.

1. A RADIO RECEIVER USABLE FOR BOTH CONVENTIONAL BROADCAST RECEPTION ANDFOR RECEPTION OF WARNING SIGNALS COM-/ PRISING, CIRCUIT MEANS TUNABLE TOBOTH BROADCAST AND WARNING SIGNALS, DETACHING MEANS FOR DERIVING AUDIOFREQUENCY SIGNALS FROM THE RECEIVED SIGNALS, A VOLUME CONTROL COUPLED TOSAID DETECTING MEANS OR CONTROLLING THE AMPLITUDE OF SAID AUDIO SIGNALS,AMPLIFIER MEANS FOR SAID AUDIO SIGNALS, MEANS FOR CONTROLLING THEOPERABILITY OF SAID AMPLIFIER MEANS, SELECTIVE CIRCUIT MEANS COUPLED TORECEIVE AUDIO FREQUENCY SIGNALS DERIVED BY SAID DETECTING MEANS ANDRESPONSIVE TO SIGNALS OF A PREDETERMINED FREQUENCY TO DEVELOP AN OUTPUTPOTENTIAL, AND TWO-POSITION CONTROL SWITCH MEANS OPERABLE IN ONEPOSITION TO CONNECT THE RECEIVER TUNABLE CIRCUIT MEANS FOR CONVENTIONALBROADCAST RECEPTION, COUPLE THE DETECTOR OUTPUT THROUGH SAID VOLUMECONTROL TO SAID AMPLIFIER MEANS, AND RENDER SAID AMPLIFIER MEANSOPERATIVE, AND OPERABLE IN THE OTHER POSITION TO TUNE SAID RECEIVER FORWARNING SIGNAL RECEPTION, COUPLE THE DETECTOR OUTPUT DIRECTLY TO SAIDAMPLIFIER MEANS, AND COUPLE SAID SELECTIVE CIRCUIT MEANS TO SAIDCONTROLLING MEANS FOR SAID AMPLIFIER MEANS TO RENDER THE LATTER OPERABLEIN RESPONSE TO SAID OUTPUT POTENTIAL, SAID CONTROL SWITCH MEANSCORRESPONDING TO A CONVENTIOANL ON-OFF SWITCH WHEREBY SWITCHING OF SAIDRECEIVER TO DISCONTINUE CONVENTIONAL BROADCAST RECEPTION NECESSARILYCONNECTS THE RECEIVER FOR WARNING SIGNAL RECEPTION.